Method and apparatus for sterilizing the interior of a vessel containing a fluid with some void space allowed therein

ABSTRACT

A method for thermally sterilizing the interior of a vessel containing a fluid with some void space allowed therein comprises moving the vessel so as to cause the fluid contained therein to flow over its entire inner walls and irradiating microwave energy to the vessel while it is moved.

United States Patent 1 1 Nagao et a1.

n 1 3,737,608 1 1 June 5,1973

[54] METHOD AND APPARATUS FOR STERILIZING THE INTERIOR OF A VESSEL CONTAINING A FLUID WITH SOME VOID SPACE ALLOWED THEREIN Inventors: 'Tsuguki Nagao; Toshihiko Toishi,

both of Tokyo, Japan Assignee: Tokyo Shibaura Electric Co., 1.01.,

Kawasaki-sin, Japan Filed; May 28, 1971 Appl. No.: 148,098

. Foreign Application Priority Data References Cited.

UNITED STATES PATENTS 3,674,422 4/1972 Gray ..2l9/l0.55 2,058,826 10/1936 Reece ..2l/102 R 2,095,502 10/1937 Johnston ..2 H80 X 599,205 2/ l 898 .Vause 99/249 3,494,722 2/1970 Gray ..2l9/l0.55 X

3,481,266 Puschner ..99/253 Primary Examiner J. V. 'iruhe Assistant Examiner-Hugh D. Jaeger Attorney-Kemon, Palmer'8z Estabroolt [5 7] ABSTRACT A method for thermally sterilizing the interior of a vessel containing a fluid with some void space allowed therein comprises moving the vessel so as to cause the fluid contained therein to flow over its entire inner walls and irradiating microwave energy to the vessel while it is moved. I I

2 Claims, 13 Drawing ri -m METHOD AND APPARATUS FOR STERILIZING THE INTERIOR OF A VESSEL CONTAINING A FLUID WITH SOME VOID SPACE ALLOWED THEREIN This invention relates to a method and apparatus for sterilizing the interior of a fluid-containing vessel by applying microwave energy to the fluid.

Fluid materials are generally handled as contents of a vessel. Among these fluid materials, certain kinds of liquid medicine and beverage should be preserved in a vessel in a sterilized state free from harmful germs.

However, it often happens that miscellaneous germs are carried into a vessel due to the imperfect washing of its interior or while it is filled with a fluid material. Therefore, it is general practice to apply low or high temperature sterilization to the vessel after it is sealed. Thermal sterilization is generally effected by, for example, application of infrared rays or boiling. These processes only heat the outer surface of a vessel, so that there is required unduly long time for the interior of a substance contained therein to be heated up to a prescribed temperature for sterilization. Moreovenheating is conducted ununiformly. There has been proposed another thermal sterilization method using microwaves. However, this method is accompanied with the following drawback. Generally, liquid medicine is received in an ampule in a manner to occupy half or one-third of its inner volume, with the remaining space filled with a gas compressed with a higher pressure than the atmospheric, When microwaves are applied to such ampule, the portion mainly heated is only the medicine contained therein. Those inner walls of the ampule which are not contacted by the medicine but exposed to the gas are notpractically heated. This is due to the fact that the ampule made of glass or plastics material does not absorb high frequency waves and causes heat to be unduly radiated due to its thin walls. Therefore, even when the medicine in the ampule is heated to a sufficiently high temperature to obstruct the growth of miscellaneous germs, residual germs settled on the inner walls do not perish. Moreover, if microwaves continue to be applied, the medicine will eventually boil, causing the ampule to be damaged due to the resulting excessive vapour pressure.

It is accordingly the object of this invention to provide a method and apparatus for fully sterilizing the interior of a fluid-containing vessel by irradiation of microwaves.

According to an aspect of this invention, there is provided a method for sterilizing the interior of a vessel containing a fluid containing void space which comprises moving the vessel insuch a manner as to cause the fluid contained therein to flow over its entire inner walls and applying microwave energy to the vessel while it is being moved.

According to another aspect of the invention, there is provided an apparatus for sterilizing the interior of a vessel containing a fluid with some void space allowed therein, which comprises a microwave power source; a microwave oven; a waveguide for conducting microwaves from the microwave generator to the microwave oven; and a support member provided in the microwave oven for moving the vessel so as to cause the fluid contained therein to flow over its entire inner walls.

This invention can be more fully understood from the following detailed description when taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic sectional view of a microwave sterilizer according to an embodiment of this invention;

FIG. 2A represents another embodiment of the invention; v

FIG. 28 illustrates the manner in which the Si rilizer of FIG. 2A is operated;

FIG. 3A shows another embodiment of the invention;

FIG. 38 indicates the manner in which the sterilizer of FIG. 3A is operated;

FIG. 4A is a schematic illustration of still another embodiment of the invention; A

FIG. 4B is a sectional view on line 4B,'4B of FIG. 4A;

FIG. 5 indicates a further embodiment of the invention;'

FIG. 6 is a schematic perspective view of a still further embodiment of the invention;

FIG. 7A shows the condition of vessels when the vessel support of FIG. 6 is not rotated;

FIG. 7B indicates the condition of vessels when the vessel support of FIG. 6 is rotated;

FIG. 8 is a schematic perspective view of a still further embodiment of the invention; and

FIG. 9 shows the construction of the vessel support of FIG. 8.

There will now be described specific embodiments of this invention by reference to the appended drawings. Throughout the figures, the same parts are denoted by the same numerals. Referring to FIG. 1, there is formed a microwave irradiation window 4 at the top 3 of a metal microwave oven 2 mounted on a 1. To the microwave irradiation window 4 is'connected through a waveguide 5 a microwave power source 6, for exam ple, a magnetron. In themicrowave oven 2 is disposed a vessle support member 7 permissibly made of metal and rockably supported at one end. A drive rod 8 for rocking the support member 7 penetratesthe base 1 and the bottom 9 of the microwave oven 2 to abut at the inner end on the underside of the support member 7 near its free end and contact a cam 11 driven by a motor 10 at the other end. On the supportmem ber7 is mounted a holder 12 of vessels, for example, ampules which consist of a material minimizing'the loss of high frequency waves such as polytetrafluo'roethylene, polypropylene or silicone rubber. To the'holder 12 are attached ampules 13 with the pointed end directe'ddownward. Reference numeral 14 represents a known stirrer fan for distributing microwaves in all directions within the oven 2, and 15 denotes a known choke'portion for preventing the outward leakage of microwaves.

When the support member 7 is repeatedly rocked by motor drive, the liquid medicine in the ampule l3 is distributed throughout its interior. When, under such condition, the microwave power source 6 is actuated, the whole of the ampule is fully heated by microwave energy. For example, where there was applied oneminute microwave enerby of 2450 MHz and 2 Kw to one hundred glass ampules each of 5 cc containing 2 cc. water to which there were purposely added hay bacilli, the ampules, as well as the content, were heated to C, presenting a full sterilizing efi'ect.

FIG. 2A shows another embodiment of this invention, wherein microwaves are irradiated on ampules while they are rolled in a microwave oven. To this end,

there is provided a belt conveyor 16 for carrying ampules thereon which are to be forwarded by the motor through the oven 2 in the direction of the arrow. The belt conveyor is formed of the same material as described above which minimizes loss of high frequency waves. There is also provided a cover plate 17 made of the same material as the belt conveyor 16 and fixed in the oven by proper means (not shown) so as to allow ampules placed on the belt conveyor 16 to be rolled.

The belt conveyor 16 has pawls 18 formed on its upper surface as illustrated in FIG. 2B which engage ampules 13. As apparent from this figure, the ampules 13 whose top contacts the cover plate 17 are sent forward in the direction of the arrow a through the oven 2 while rolling counterclockwise in the direction of the arrows b, thus causing the liquid medicine in the ampule 13 to be distributed over its entire inner walls. When, under such condition, there are irradiated microwaves, the interior of the ampule 13, as well as its content, are fully sterilized.

The reference numerals 21 and 22 in FIG. 2A are known lossy portions provided around the inlet 19 and outlet of the oven 2, which consist of a vessel made of, for example, polypropylene and filled with water or sand so as to prevent the outward leakage of microwaves.

FIG. 3A is a modification of FIG. 2A, which is designed to cause ampules 13 to roll by gravitational fall. To this end, there are provided in the oven 2 inclined chutes 25, 26 and 27. When ampules 13 are placed on the first chute 25 at the upper inlet 19 of the oven 2, they roll down the first, second and third chutes 25, 26 and 27 in turn to be taken out of the lower outlet 20 of the oven 2. In this case, there is produced the same sterilizing effect as in the preceding case. The lower end portions of the chutes may be provided with shutter means 28 and 29 driven by proper device (not shown) so as to allow the ampules 13 to fall'one by one on to the succeeding chutes. In FIG. 3A, the ampules on the chutes are prevented from falling on to the succeeding ones by the shutter means 28 and 29, while in FIG. 3B, the lowest ampule l3 alone is allowed to fall on to the following chutes due to the movement of the shutters 28 and 29.

Referring to FIG. 4A, the reference numeral 30 shows a cylindrical ampule guide penetrating the microwave oven 2. This guide is made of the same material as in the preceding cases which minimizes loss of high frequency waves and has four guide grooves 31, 32, 33 and 34 formed lengthwise along the outer periphery as shown in FIG. 4B. Ampules 13 are fitted into the guides 31, 32, 33 and 34 as illustrated in FIG. 4A. After the ampules 13 are placed in the grooves, the cylindrical ampule guide 30 is covered with sleeves 35 formed of the material which similarly reduces loss of high frequency waves. The cylindrical ampule guide 30 is made to travel from the inlet 19 to the outlet 20 of the oven 2, and at the same time rotate clockwise as indicated in FIG. 4B. Therefore, the embodiment of FIG. 4A has the same full sterilizing effect as the preceding embodiments.

Referring to FIG. 5, the reference numeral 36 is an ampule-holding chuck portion fitted to a shaft 37, one end of which extends into the oven 2. This chuck portion 36 is formed of the same material as in the preceding embodiments which minimizes loss of high frequency waves. To the outer end of the shaft 37 is fitted a pulley 38 which is coupled with a motor (not shown) by a belt 39. According to the embodiment of FIG. 5,

there are irradiated microwaves while the motor is stopped. When the chuck portion 36 is rotated upon the drive of the motor, the ampules are fully sterilized in the same manner as in he foregoing cases.

Referring to FIG. 6, the reference numeral 40 denotes a rail disposed above the oven 2. To this rail 40 is rotatably fitted a shaft 41, to the upper end of which there is fixed a pulley 42, and to the lower end of which there is attached an ampule holder 43. The rail 40 is made to travel in the direction of the arrow. To this end, there is formed in the upper surface of the oven 2 a slit 44 extending throughout the surface so as to guide the shaft 41 through the oven 2. When the shaft 41 enters the slit 44 by the movement of the rail 40, the ampule holder 43 is introduced into the oven 2 through the inlet 19. Under this condition, the ampule holder 43 is carried forward in the travelling direction of the rail 40. When the ampule holder 43 is brought near the center of the oven 2, the pulley 42 fitted to the top of the shaft 41 rotates by contact with a belt 45 driven by a motor 10, causing the ampule holder 43 to rotate substantially at the center of the oven 2. When the pulley 42 is released from the belt 45, the ampule holder 43 stops its rotation and is brought to the outlet 20 of the oven 2 by the movement of the rail 40. FIG. 7A represents the condition of the ampules 13 when the ampule holder 43 does not rotate. At this time, the liquid medicine contained the ampule 13 remains at the bottom. Upon rotation of the ampule holder 43, the medicine is brought upward by the centrifugal force applied thereto as shown in FIG. 7B. Therefore, the alternate rotating and non-rotating operation of the ampule holder 43 in the oven 2 enables the ampule 13 to be fully sterilized. Those parts of the ampule holder 43 which are brought into contact with ampules 13 are made of the same material as in the preceding embodiments which minimizes loss of high frequency waves.

The embodiment of FIG. 6 is provided with a lossy or choke portion (not shown) as in the preceding embodiments to prevent microwaves from leaking out of the openings of the oven 2.

According to the embodiment of FIG. 8, the ampule holder is shaken by the action of a spring. The holder 50 is mounted, as shown in FIG. 9, on metal supports 51 and 52 having leg portions 51A and 52A, the

lower ends of which are fitted into two pairs of slits 54 and 55 respectively formed in a metal belt 53. The ampule holder 50 and supports 51 and 52 are penetrated by rods 56 and 57, the lower ends of which contact those portions of the belt 53 defined between the respective pairs of slits 54 and 55. The ampule holder 50 is normally urged upward by springs 58 and 59 stretched between the metal supports 51 and 52 and the belt 53. q

The belt 53 moves in the direction of the arrow of FIG. 8. When the ampule holder 50 is brought to a section A near the inlet 19 of the oven 2, it is forced downward by metal rails 60 and 61. When the ampule holder 50 leaves the rails 60 and 61 by further movement of the belt 53, it is vertically shaken at a section B, as shown by the arrows, by the action of the springs 58 and 59. When the ampule holder 50 further advances to a section C, it is gradually forced downward by downwardly bent rails 62 and 63 to stop its shaking. The ampule holder 50 consists of the same material as .well serve to prevent discharges of microwave energy from the springs 58 and,59.

This invention is adapted to-sterilize the interior of 5 capped bottles or other vessels in addition to ampules. And the materials to be sterilized include not only liquid medicine, but also other fluid materials requiring sterilization such as milk, juice or other beverage.

What we claim is:

1. An apparatus for sterilizing the interior of ampuls each having a neck portion and a body portion and containing a liquid medicine with some void space therein comprising:

a microwave power source;

a microwave oven; 1

a waveguide for conducting microwaves from said microwave power source to said microwave oven; an ampul holder for supporting ampuls with their neck portions directed downward; and

means for moving said ampul holder up and down within said microwave oven.

2. An apparatus for sterilizing the interior of ampuls each having a neck portion and body portion and containing a liquid medicine with some void space therein comprising:

a microwave power source;

a microwave oven;

a waveguide for conducting microwaves from said microwave power source to said microwave oven; an ampul holder for supporting ampuls with their neck portions directed downward; conveyor means for moving said ampul holder hori zontally in said microwave oven;

spring means for urging upward said ampul holder on said conveyor means; and

means provided in said microwave oven for forcing downwardly said ampul holder against the force of said spring means until said ampul holder further moves and disengages therefrom, thereby to permit said spring means to move said ampul holder up anddown. 

1. An apparatus for sterilizing the interior of ampuls each having a neck portion and a body portion and containing a liquid medicine with some void space therein comprising: a microwave power source; a microwave oven; a waveguide for conducting microwaves from said microwave power source to said microwave oven; an ampul holder for supporting ampuls with their neck portions directed downward; and means for moving said ampul holder up and down within said microwave oven.
 2. An apparatus for sterilizing the interior of ampuls each having a neck portion and body portion and containing a liquid medicine with some void space therein comprising: a microwave power source; a microwave oven; a waveguide for conducting microwaves from said microwave power source to said microwave oven; an ampul holder for supporting ampuls with their neck portions direCted downward; conveyor means for moving said ampul holder horizontally in said microwave oven; spring means for urging upward said ampul holder on said conveyor means; and means provided in said microwave oven for forcing downwardly said ampul holder against the force of said spring means until said ampul holder further moves and disengages therefrom, thereby to permit said spring means to move said ampul holder up and down. 